PATTERNS OF SEEDLING RECRUITMENT IN WEST-MEDITERRANEAN QUERCUS-ILEX FORESTS INFLUENCED BY CANOPY DEVELOPMENT

Quercus ilex (helm oak) coppice forests belong to the most representat ive communities in the western part of the Iberian Peninsula. Due to t he high sprouting potential of helm oak after coppicing, the dynamics of recruitment of new individuals in existing populations has been lar gely overlooked. In these forests, the density of seedlings increases in old stands, as a result of the remarkable increase in the recruitme nt of 1-yr and 2-yr old seedlings, probably due to better environmenta l conditions for germination. Older seedlings show a tendency towards increasing survival under some degree of canopy closure, since their d ensity appears to be higher just before complete canopy closure takes place. Nevertheless, the reduced growth of seedlings in older stands d ue to low light levels causes age distributions of helm oak seedlings to change drastically, with saplings older than 15 yr becoming very un usual in these stands. Therefore, a bottleneck of recruitment appears at this sapling stage and prevents vigorous regeneration just before t hinning. Present conditions of genet density and management tend to pr event population renewal. Dynamics of the seedling bank reinforce the role of gap formation through small or large scale perturbations in po pulation turnover.